# Thyroid Surgery

> Thyroid surgery for BDS General Surgery — swelling classification, investigations with FNAC, cancer types, thyroidectomy levels and complications like RLN palsy.

- Canonical URL: https://prepelephant.com/topics/bds/general-surgery/thyroid-surgery-bds
- Exam / course: BDS · Subject: General Surgery
- Publisher: PrepElephant (https://prepelephant.com) — Prepared and reviewed by the PrepElephant Academic Review Team
- First published: 2026-10-02
- Last updated: 2026-10-02
- How to cite: "Thyroid Surgery", PrepElephant, https://prepelephant.com/topics/bds/general-surgery/thyroid-surgery-bds

## Direct answer

A neck swelling that moves upward on swallowing is attached to the larynx — that single clinical sign places almost every thyroid lump before a single investigation is ordered. Thyroid swellings are classified as diffuse (colloid goitre, Graves' disease, thyroiditis), multinodular, or solitary nodular, and each carries a different malignant risk: a solitary hard nodule in a man over 40 is suspect; a long-standing multinodular goitre rarely hides cancer. Workup runs TSH first, then ultrasound and fine-needle aspiration cytology, reported on the Bethesda categories that steer surgery. The four malignancies behave in examinably different ways — papillary (commonest, lymphatic, excellent prognosis), follicular (haematogenous), medullary (calcitonin, MEN syndromes), anaplastic (elderly, rapidly lethal). Thyroidectomy itself is graded — hemi, subtotal, near-total, total — and its feared complications are recurrent laryngeal nerve palsy, hypoparathyroid hypocalcaemia in the first 48 hours, and haematoma compressing the airway.

## What you must remember

- **The swallowing and tongue-protrusion rules:** thyroid swellings ascend on swallowing (tethered to the larynx by pretracheal fascia); a thyroglossal cyst additionally moves on tongue protrusion — the two signs that structure every neck-lump viva.
- **Classification:** diffuse nontoxic colloid goitre (iodine deficiency — the reason India runs a national iodised-salt programme), diffuse toxic goitre of Graves' with eye signs, multinodular goitre, solitary nodule, thyroiditis, and malignancy.
- **Investigation ladder:** TSH (with T3/T4 if abnormal), ultrasound for solid versus cystic and node mapping, FNAC as the decisive test (Bethesda I nondiagnostic to VI malignant), radioisotope scan to separate hot from cold nodules — a cold solitary nodule in a male over 40 carries the highest cancer risk.
- **Cancer quartet:** papillary — commonest, psammoma bodies, lymphatic spread, excellent survival; follicular — blood-bone spread, diagnosed on vessel invasion; medullary — calcitonin-secreting, C-cell origin, MEN 2A/2B association; anaplastic — elderly, rapidly enlarging, tracheal obstruction, poor prognosis.
- **Operations by name:** hemithyroidectomy (one lobe with isthmus), subtotal (Graves', leaving rims), near-total or total thyroidectomy (bilateral malignancy), plus prophylactic total thyroidectomy in MEN 2 carriers.
- **Complications with clocks:** hoarseness from recurrent laryngeic nerve injury (bilateral injury stridors and needs urgent airway); perioral tingling and carpopedal spasm from hypocalcaemia on day 1-2 (parathyroids bruised or removed — give calcium, sometimes vitamin D); haematoma within hours (open the wound at the bedside if the airway is threatened); thyroid storm in uncontrolled thyrotoxicosis; hypothyroidism after total thyroidectomy needs lifelong thyroxine.
- **Thyroid storm:** tachycardia, fever, agitation, arrhythmia days after surgery on an untreated toxic goitre — beta-blockers, propylthiouracil, iodine, steroids and cooling.

## Choosing the operation for four different nodules

Four outpatient stories, four correct operations. A 25-year-old woman with a smooth diffuse swelling, euthyroid on testing and benign on FNAC: colloid goitre — observe or suppress, operating only for cosmesis or compression. A 38-year-old with a solitary cold nodule, Bethesda V: hemithyroidectomy with frozen section, proceeding to total thyroidectomy if follicular or papillary carcinoma is confirmed, because a follicular tumour's malignancy is proven only by vascular or capsular invasion on histology. A 60-year-old with a rapidly enlarging hard mass, hoarseness and stridor: anaplastic carcinoma until proven otherwise — biopsy, airway planning (often tracheostomy), chemoradiation; surgery rarely cures. A 30-year-old with a neck node, a thyroid nodule and a family history of medullary cancer: calcitonin and RET proto-oncogene testing, prophylactic total thyroidectomy in gene carriers, sometimes before the disease ever appears. The exercise teaches the real surgical skill — matching the extent of surgery to the pathology — and why the FNAC, not the size of the lump, drives the consent form.

## Where students slip

The standard viva error is calling every midline neck swelling a goitre: thyroglossal cysts (move on tongue protrusion), submental nodes, dermoid cysts and bony swellings all queue at the same midline. The second slip is the hyperthyroid versus hypothyroid sign mix-up — Graves' disease pairs eye signs (lid lag, exophthalmos) with tremor, weight loss and heat intolerance, while myxoedema dulls everything; examiners present a vignette and expect instant sorting. Third, the calcium question: hypocalcaemia after thyroidectomy appears on day 1-2 with perioral paraesthesia and a positive Chvostek sign — checking it is part of post-thyroidectomy ward rounds, and the BDS viva expects both the timing and the sign.

## Frequently asked questions

### Why does a thyroid swelling move on swallowing?

The gland is invested by pretracheal fascia attached to the larynx, so it ascends with the larynx during deglutition — a clinical signature shared by thyroglossal cysts but not by most other neck lumps.

### Which thyroid cancer has the best prognosis and which the worst?

Papillary carcinoma, with 10-year survival above 90 per cent even with nodal spread, versus anaplastic carcinoma, which kills most patients within months of diagnosis.

### How does hypocalcaemia present after thyroidectomy?

Perioral and fingertip tingling, carpopedal spasm, positive Chvostek and Trousseau signs, typically on the first or second postoperative day from parathyroid bruising, removal or devascularisation.

### What does a cold solitary thyroid nodule on isotope scan signify?

A non-functioning nodule with the highest malignant potential of thyroid swellings — FNAC is mandatory before deciding management.

### Which nerve is at risk in thyroidectomy and what is the effect of injury?

The recurrent laryngeal nerve — unilateral injury causes hoarseness, bilateral injury causes airway obstruction with stridor demanding urgent intervention.